Title

Versatile route for syntheses of pi-conjugated polymers and device fabrication

Date of Completion

January 2008

Keywords

Chemistry, Polymer

Degree

Ph.D.

Abstract

In this dissertation, a process for producing 3,4-ethylenedioxythiopene (EDOT) and 3,4-propylenedioxythiophene (ProDOT) containing π-conjugated conducting polymers (CP) via solid state oxidative conversion (SOC) of novel processable poly(arylene-alt-silylene) (the silane) precursors is reported. The primary advantage is the processability in the precursor stage, and conversion to CP after the desired shape has been casted. The significance of the preparation and conversion of the silane precursors is due to the emergence of poly(EDOT) (PEDOT) over the years as an industrially applicable material for the production of optically transparent conductive coatings, hole injection layers in organic light emitting diodes and organic photovoltaics, to name a few. High molecular weight silanes are prepared in good yield in one pot from aryl moiety and dialkyldichlorosilane. The precursors have good thermal properties, store well, and processing via conventional techniques (e.g. dip, spin, spray coating etc.) is feasible.^ Two modes of solid state precursor conversion to CP are described: (1) Electrochemical (Chapters 3, 4) and (2) Solvent-free bromine vapor (Chapter 5). In the former, films of the precursor on the working electrode are converted to CP by electrodesilylation in the presence of an electrolyte. In the latter approach, exposure to bromine vapor followed by heat, ensues a tandem bromodesilylation and in-situ couplings generating CP with poly(dimethylsiloxane). Previous reports of solid state polymerization in crystalline small molecules are therefore complemented with amorphous polymeric systems.^ Conducting π-conjugated polymers (CPs) attract much attention from academia and industry as they offer specific advantages over inorganics by virtue of their polymeric nature. The rigid π-conjugated backbone, however, render them insoluble, intractable, and infusible. Thus, the wide variety of processing technologies for commodity plastics cannot be applied to these elite materials. In order to harness these materials as commercially viable products, processing of these materials into devices is crucial. The work outlined herewith suggests a step towards overcoming this hurdle, and make conjugated polymers industrially attractive. The conversion of poly(arylene- alt-silylene) to predominately CP can be applied to a multitude of thiophene monomers and is anticipated to be applicable to furans, pyrroles and other heteroaromatics. ^